Guitars and Humidity

[whosgarethparry]

I have a 335 style guitar. Made 30 odd years ago. Until last yr, it was a fairly stable climate in the uk, in terms of humidity.

In sept I moved to Canada which has particularly dry winter's and very humid summer's.
My question is thus, How much do you think humidity affects a semi hollow? Should I be overly concerned.
Secondly, should I get a dehumidifier etc? I gig alot, plus rehearsals, so it seems pointless to control my home environment, then take it out most days into the unknown?
Any advice would be great guys?

[Gabe]

You could get a case humidifier if you're really concerned. I use the Planet Wave Humidipacks for my acoustics, but my semi doesn't have one - I might get one at some point though, it's better to be cautious I think.

[PTChristopher]

I think that this is a great general question.

My opinion involves more than yes or no, sorry; skip the post if that is a problem for you.

>>> How much do you think humidity affects a semi hollow?

Far less than a solid-wood acoustic (arch, flat or classical), but it still has a significant effect.

The effect is mostly experienced on the neck. The FB and neck get quite a bit wider in the humid summer and narrower in the dry winter. Also, the relief will typically change considerably for two reasons (which I'll leave out for this post).

>>> Should I be overly concerned.

No. Constant humidity is always easier on the wood, but for a plywood semi that is designed to be a day-in day-out battle axe, I would not expect any sort of trouble (splitting tops, etc.) like you can get on more fragile guitars.

But,...

>>> Secondly, should I get a dehumidifier etc? I gig alot, plus rehearsals, so it seems pointless to control my home environment, then take it out most days into the unknown?

Depends. While a rapid and extreme temperature change can give trouble over a short period, pure environmental humidity changes take a while (days typically) to have any appreciable effect.

>>> it seems pointless to control my home environment, then take it out most days into the unknown?

Not really. If the guitar spends 16 hours per day in your controlled home environment, then 8 hours per day in a seasonal extreme environment, the net effect on the guitar will be far less than you might think. So case humidity control, or room humidity control has a significant benefit even for a full-time gigging musician.

So take your pick:

- Forget about it. The seasonal cycle can almost certainly be handled with some truss rod adjustments as needed. You can easily learn to do this extremely well - better than your luthier since after a year you'll get to really know the guitar and how it will react to humidity and your adjustments.

OR

- Control the humidity in the room (or case) in which the guitar spends its home time. This has a big impact even though the guitar is out making a living much of the time. Yes the guitar will be drier in the winter and wetter in the summer, but the net effect will be much reduced vs. doing nothing.

Both methods are used and both have mostly happy players. And both have the occasional unhappy player.

Chris

[whosgarethparry]

as ever Chris, an amazingly well written and detailed reply. Thanks man. I'll look into a case humidifier, as room dehumidifiers are a bit more expensive! i switched to a hiscox pro case rather than a gig bag because i heard cases offer a modicum of protection, due to it taking longer for the ambient temp in the case to change.....i guess if i think it makes a difference, it makes a difference, right??

[Eddie Lang]

Hi. Chris' reply covers it pretty well.

Gareth, you probably meant "room humidifier", not "dehumidifier". Two very different devices...

If you have only this one guitar to care for, a case humidifier will do the trick. It is good to also have an hygrometer in the case to be sure that the RH is about 40%-50%. Over-humidifying is bad too.

A room humidifier will be a good solution if you have multiple guitars and they stay out of their case most of the time. An hydrometer in the room may or may not be recommended. Even if most room humidifier have pretty controls and will start/stop automatically depending of the relative humidity, their level of accuracy may vary depending on the model. You be the judge.

Personally, I find it easier to control the humidity level of a room rather than several cases, but others may have the contrary opinion and be just as right...

[Gabe]

Speaking of hygrometers, what is the general consensus on these. I'm thinking about buying some for my guitar cases so the small and cheap ones look ideal.

[PTChristopher]

This brings up two things:

>>> [Bag vs. case] i guess if i think it makes a difference, it makes a difference, right??

Har-har. I do think you can expect the Hiscox to be a better humidity and temp buffer vs. a bag. Plus easier to humidify.

>>> Over-humidifying is bad too.

Yep. I have run into mold inside hollow body guitars from EHE (Excessive Humidification Enthusiasm). Damp-It products are often a culprit here. They are just fine, but it is easy to have them too wet and dripping inside the body. I have yet to see serious wood damage though, only mold.

Just make sure whatever you use does not end up leaking liquid anywhere.

>>> dehumidifier

Under some conditions (hot/cold cycles in damp weather) you may do very well to consider dehumidifying. Check out Zorb-It packs as one way to do this.

But most people only worry about excessive dryness.

In my opinion hygrometers are remarkably inaccurate. I have 5 or 6 and they all disagree to various degrees under all conditions. I have cheap ones and expensive ones and they are all over the place. I would assume +/- 10% accuracy, at best, based on the scatter of even my ostensibly good and accurate hygrometers.

All in my opinion.

Chris

[oldane]

The effect is mostly experienced on the neck. The FB and neck get quite a bit wider in the humid summer and narrower in the dry winter.

One could add, that this shrinking of the fretboard in the dry season can even cause the fret ends to protrude a bit. I have experienced this a few times with guitars built in the (more humid) summer time when the first winter came. It's not a big problem as it's fast and not difficult to file down the fret ends flush with the fretboard and then round the fret ends with a dressing file. I did it shortly after new year with a new guitar which was built last summer and which I recieved in october. The whole operation took me about an hour.

BTW, this possible protruding of fret ends in dry seasons is the reason I don't like binding nibs. With nibs, the nibs and the binding will be pressed outwards by the frets and may crack and/or breake. Also, one can't do that simple fret end filing with nibs.

[Patrick2]

In my opinion hygrometers are remarkably inaccurate. I have 5 or 6 and they all disagree to various degrees under all conditions. I have cheap ones and expensive ones and they are all over the place. I would assume +/- 10% accuracy, at best, based on the scatter of even my ostensibly good and accurate hygrometers.

With well over a dozen carved solid wood arch tops always sitting on nitro friendly stands, where I can easily see them and reach out for them, I am very diligent in my management of the temp and RH in my guitar room. I have three different types of hygrometers in that room, with 4 others throughout my home. While what Chris says about the inconsistency of hygrometers is absoultely true . . . the very best of them are ususally dead nuts on. I have a nephew who works in a major pharmaceutical plant. He is in the plant maintenance department. His company provided monitoring equip for the environment in plant is very expensive and must be calibrated every 3 months for accuracy. About 4 months ago, he brought me 2 high end hygrometers. One he owns (an Extech) and one he "borrowed" from the compay. I used the more expensive of the 2, a Dickson TH300, to check out all of the others in my home. I found that all of the less expensive ones that I owned ran 10% to 20% plus of the Dickson. The one he owns (well, I own it now) ran a very consistent 10% plus of the Dickson. I ran the tests for 3 weeks, then he had to return the Dickson to his plant tool crib. So, now I know that when the Extech (the other high end hygrometer, which he has now given to me) is showing 50% RH . . . it's really more like 45% RH in my guitar room. I consider anything between 35% and 55% RH to be acceptable and safe . . . . with 45% RH being optimal.

As Chris mentioned, the swings and fluctuation of RH is what does the most damage in the short term. While the greatest damage is long term exposure to extremely dry air . . . . 20% and lower RH.

I have an April Air whole house humidifier on my furnace . . (my home is heated by forced warm air . . which really dries out the air). I also have a console humidifier in my guitar room. My guitar room usually runs between 42% and 48% RH consistently. I haven't had to "tweak" a truss rod in over 2 years. My guitars are .... happy.

[Eddie Lang]

In my opinion hygrometers are remarkably inaccurate. I have 5 or 6 and they all disagree to various degrees under all conditions. I have cheap ones and expensive ones and they are all over the place. I would assume +/- 10% accuracy, at best, based on the scatter of even my ostensibly good and accurate hygrometers.

What most people don't know or forget is that hygrometers, even expensive ones, need to be calibrated annually -- and yes, they should be calibrated when they are fresh out of the box too...

The procedure is simple enough, using salt, water and a heavy duty ziplock bag.

[PTChristopher]

Hi Eddie,

Thanks for the info. I understand calibration, and the advised single point calibration of the salt method.

In my experience this still leaves some incredible non-linearity as an issue.

I can put all the hygrometers in a high humidity environment and either calibrate them, or note the offset. But then they scatter down in the ranges at issue in the dry winter.

But others may find this not a problem for one reason or another.

[Patrick2]

This brings up two things:

>>> [Bag vs. case] i guess if i think it makes a difference, it makes a difference, right??

Har-har. I do think you can expect the Hiscox to be a better humidity and temp buffer vs. a bag. Plus easier to humidify.

>>> Over-humidifying is bad too.

Yep. I have run into mold inside hollow body guitars from EHE (Excessive Humidification Enthusiasm). Damp-It products are often a culprit here. They are just fine, but it is easy to have them too wet and dripping inside the body. I have yet to see serious wood damage though, only mold.

Just make sure whatever you use does not end up leaking liquid anywhere.

>>> dehumidifier

Under some conditions (hot/cold cycles in damp weather) you may do very well to consider dehumidifying. Check out Zorb-It packs as one way to do this.

But most people only worry about excessive dryness.

In my opinion hygrometers are remarkably inaccurate. I have 5 or 6 and they all disagree to various degrees under all conditions. I have cheap ones and expensive ones and they are all over the place. I would assume +/- 10% accuracy, at best, based on the scatter of even my ostensibly good and accurate hygrometers.

All in my opinion.

Chris

[quote=PTChristopher;229697]I definitely understand calibration, and the advised single point calibration of the salt method.

In my experience this still leaves some incredible non-linearity as an issue.

I can put all the hygrometers in a high humidity environment and either calibrate them, or note the offset. But then they scatter down in the ranges at issue in the dry winter.

But others may find this not a problem for one reason or another.

I really don't find exact accuracy to be that much of an issue. If you have a fairly good hygrometer .. . it's going to tell you if an area is dry or humid. Even if you have a cheap hygrometer, if it reads 20% RH . . . you've usually got an issue that needs to be addressed. The reason I checked my hygrometers with a very accurate one, was to get a feel for how much they're off and in which direction. Now I can better manage the environment. My April Air unit came with a humidistat at the control and two other independent hygrometers. So, between them all, I know if my home is dry or humid. As it relates to guitars, that's all that's really necessary. A high end carved spruce top arch top guitar couldn't care less if it's in a 40% RH environment or a 45% RH environment. But, it really wouldn't be too happy in a 75% RH or 20% RH environment.

[Spook410]

Sorry for the verbose post, but this is something I feel strongly about.

I moved from Houston, Texas to Omaha, Nebraska. I had never lived in a place that actually had a winter and was focused on things other than guitars at the time. The furnace dried out the air in winter and a lot of fine flat top acoustics were damaged including a badly cracked top on a very nice Brazilian Kinscherff. I now live in the high desert in New Mexico. Certainly a more extreme environment than a heated house in a Nebraska winter, but I've learned my lesson. When a solid wood guitar goes from the humidified storage closet to a stand in the living room, it only takes about 2-3 days for the action to noticeably change. On a beater jumbo Taylor I play regularly it drops to unplayable in that amount of time.

As for your 335, the neck isn't laminate. While my Heritage 535 is much more tolerant of low humidity than the nice acoustics, it will take damage if not cared for. The aforementioned Taylor 415 I got cheap because the top and back were splitting (well made guitars.. was just the seams though the guitar had been badly abused). In addition, it had the fret ends poking out and I was worried the neck would twist. That didn't happen but I still need to work on the frets as they have not fully recovered after the guitar was humidified. If I didn't humidify the 535 and other electrics I'm certain their necks would suffer damage over time.

Finally, I use a small humidifier running part time in a closet which works great. I have a reasonable hygrometer and try to keep it close to 50-60%. Of course, with this thread I have to go play with calibration now. Also, if I were going to use something in the case I would use an Oasis. Dampits suck.

edit: Checked my Oasis hygrometer using the baggie/salt method. Reads 4% low.

[PTChristopher]

[Patrick2]>>> I really don't find exact accuracy to be that much of an issue.

Oh yeah. I definitely find mine to be notably inaccurate, but 100% agreed, they are close enough to do the job.

Chris

[whosgarethparry]

Woh, some amazing responses.
Earlier I think I meant a dehumidifier. I have a humidifier for the winter months, I was just wondering if a dehumidifier was of any value over the summer months. To try and keep a median. It seems consensus is that too dry is worse than too humid.

[Spook410]

Woh, some amazing responses.
Earlier I think I meant a dehumidifier. I have a humidifier for the winter months, I was just wondering if a dehumidifier was of any value over the summer months. To try and keep a median. It seems consensus is that too dry is worse than too humid.

"DE"-humidifier. Damn. Now we have to start all over again.

[tonedeaf]

In response to comments about swings in humidity being the big issue:

I live in a very dry environment (from 30% in the summer to less and 20% in the winter). There is no reasonable way to get 47% humidty year round in my house and I have gone with the "stable at 40%" strategy. It has worked very well for me for years -- no cracks or seperations and my guitars stay in tune. However I just recently had a very dissappointing occurance. I recently bought a beautiful, natural-blond Heritage 535 (about 15 yrs. old). After owning it for about 3 months I have noticed the finish getting hairline cracks all over the guitar.
There is no warping, joint seperation or structural cracks and the guitar still plays just fine. But boy it was heart-breaking to see this beautiful finish deteriorate.

[PTChristopher]

Wow TD,

Sorry to hear about that.

Hard to follow the flow of events in a 15 year old guitar that would lead to finish checking in a (presumably) shrinking guitar.

Ya gonna live with it or go for a re-finish some day?

I bet it still sounds and plays great.

Chris

[Patrick2]

In response to comments about swings in humidity being the big issue:

I live in a very dry environment (from 30% in the summer to less and 20% in the winter). There is no reasonable way to get 47% humidty year round in my house and I have gone with the "stable at 40%" strategy. It has worked very well for me for years -- no cracks or seperations and my guitars stay in tune. However I just recently had a very dissappointing occurance. I recently bought a beautiful, natural-blond Heritage 535 (about 15 yrs. old). After owning it for about 3 months I have noticed the finish getting hairline cracks all over the guitar.
There is no warping, joint seperation or structural cracks and the guitar still plays just fine. But boy it was heart-breaking to see this beautiful finish deteriorate.

As I'm sure you know, the "hairline cracks all over the guitar" is called crazing or checking. It's fairly common place with many guitars that are finished in real and true nitro cellulous lacquer. It may . . . or may not have been caused by fluctuations in RH. Or, it may or . . . may not have been caused by swings or fluctuation in temperature. Or, by fluctuations in both. But, it is most commonly caused more by temp than by RH. Also, your guitar's finish is certainly NOT deteriorating. It's . . . "maturing"

There are kids who are paying all sorts of stupid amounts to have their strats and Les Pauls relic'd. "Skilled artisans" are painstakingly cutting those hairline cracks into beautiful guitars with a razor blade and charging obscene amounts of money to do it. Go figure!!

[Patrick2]

Wow TD,

Sorry to hear about that.

Hard to follow the flow of events in a 15 year old guitar that would lead to finish checking in a (presumably) shrinking guitar.

Ya gonna live with it or go for a re-finish some day?

I bet it still sounds and plays great.

Chris

Chris . . . the Heritage natural finishes are either blond, or antique blond. With the antique blond, a TINY bit of colorant is mixed in with the clear nitro to give it an aura of patina. If TD's guitar is antique natural, a little bit of naturally created checking will make it look way cool. Picture a '58 unbound FB ES335 in natural, after decades of gigging in a smokey grungy blues bar . . in and out of the "elements" during many many winters and summers. Vibe to spare!!!

[PTChristopher]

Hiya Patrick,

>>> [wholesale crazing] it is most commonly caused more by temp than by RH

Definitely agreed. And seemingly demonstrated by cold temps in the baggage hold of an airliner.

>>> Vibe to spare!!!

Yep.

Still bothersome to see if unexpected, so I can understand someone lamenting it to some extent.

Chris

[geoffsct]

I live @ 8200' in a pretty dry area. I never paid much attention to hydrating and now my 335 really shows it. The big problem is that I'm gone sometimes several months at a time and don't know how I could keep an area moist or of a guitar hydrater that wouldn't dry up in a couple of weeks. Now that I've gotten into some nice fatter archtops I'm looking for an answer to this. I'm also wondering if a guitar can be successfully RE-hydrated and what that process might be.

[fws6]

Submerging in a bathtub overnight will do the trick

[bananafist]

fws6 - probably not the answer the op was after.

[ESCC]

Submerging in a bathtub overnight will do the trick

Can you play the guitar while in the tub or is it best to let it soak alone?

What I do is place the guitar(s) in a relatively normal to small sized room with a humidifier running.